DESCRIPTION OF THE PRIOR ART
It is necessary to provide a containment assembly for a gas turbine engine so that in the event of a rotating part of the engine becoming detached it will be prevented from passing through the engine casing. Containment of a rotating part, such as a fan blade, which has become detached reduces the possibility of damage to the remainder of the engine or the aircraft structure to which the engine is attached.
A conventional containment assembly consists of an annulus which is placed around the engine casing. Containment rings have in the past been manufactured from metal. Metal containment rings are manufactured from relatively thick sections of metal to ensure that they have adequate strength. This results in a heavy structure which is particularly undesirable in the case of an aircraft gas turbine engine.
Composite containment rings are obviously much lighter than metal ones, however the composite ring distorts as it absorbs the energy of the failed component. The distortion travels around the composite containment ring dissipating the energy of the component.
As gas turbine engines increase in diameter, to provide more thrust, the distance between the engine support structure, such as a pylon attached to the aircraft fuselage, and the engine casing decreases. In some instances the engine is mounted so closely to the pylon that the distance between the engine casing and the pylon is less than the maximum excursion of the composite containment ring when a failed component impacts the ring. The composite containment ring interacts with the pylon and associated aircraft structure and can cause damage to either or both.